Dridex and Locky, two prolific malware families that made waves in 2016 after being distributed in several high-volume spam campaigns, have returned after a brief hiatus. FireEye observed a decline in the volume of Dridex and Locky in the latter half of 2016, but we recently observed two new large campaigns.

https://www.fireeye.com/blog/threat-research/2017/05/dridex_and_lockyret.html